Two-part electrical coupling

ABSTRACT

A two-part electrical coupling has a plurality of electrical connectors on one part for electrically engaging respective electrical connectors of the other part. The parts are provided with mating keys and keyways for ensuring that the electrical engagement can be effected only following a mechanical engagement of the parts when in one predetermined alignment and orientation with respect to one another. The keys and keyways are disposed on respective parts of the coupling and the keys are slidable along respective keyways as the two parts are urged together to establish the electrical engagement. Each key and keyway has a transverse section that is in the form of a sawtooth with unequal flanks.

United States Patent McDonald et al.

[54] TWO-PART ELECTRICAL COUPLING [72] Inventors: Thomas VictorMcDonald, Cheltenham; Kenneth McDonald Stockley, Bath, both of FOREIGNPATENTS OR APPLICATIONS 1,305,383 8/1962 France ..339/l86 R EnglandPrimary Examiner-Marvin A. Champion [73] Assignee: Smiths IndustriesLimited, London, En- Assistant Examiner-Lawrence J Staab glandAttorney-William D. Hall, Elliott I. Pollock, Fred C. Philpitt, Filed: y1970 giggle Vande Sande, Charles F. Stemmger and Robert R. [21]App1.No.: 38,664

[57] 1' Application Priority Data A two-part electrical coupling has aplurality of electrical con- Apr. 23, 1969 Great Britain ..26,336/69elecmmlly engaging respec'ive trical connectors of the other part. Theparts are provided 52 us. c1. 339/186 M, 339/217 R with m g y andkeyways for ensuring that the electrical [51] Int. Cl ..H0lr 13/64engagement can be effected only following amechanical en- [58] Field ofSearch ..339/184, 185, 186, 176 M, 65, gagement of the parts when inone-predetermined alignment 3 1 M; 52/239; 46/25 and orientation withrespect to one another. The keys and keyways are disposed on respectiveparts of the coupling and [56] References Clted the keys are slidablealong respective keyways as the two parts UNITED STATES PATENTS areurged together to establish the electrical engagement. Each key andkeyway has a transverse section that is in the 3,394,337 7/1968 Miller"339/91 form ofa awtooth with unequal flankg 2,938,190 5/1960 Krehbiel..339/l76 M 2,688,123 8/1954 Benham et al ..339/176 M 10 Claims, 7Drawing Figures PATENTEDAPRH I972 3,656,090

SHEET 2 UF 3 moms v. "won/v.0 KENNETH M.$TOCKLE'Y ayflajiwi Mum Thisinvention relates to two-part electrical couplings.

The invention is particularly concerned with electrical couplings of thekind having two parts that are adapted to engage one another in a uniquemechanical engagement before they can be finally urged together toestablish the mating of electrical connectors of one of the parts withrespective electrical connectors of the other part. By a uniquemechanical engagement" is meant a mechanical engagement that can beeflected only when there is one predetermined alignment and orientationof the parts with respect to one another.

It is common practice to provide an electrical coupling with each of itsparts provided by a housing of elongate form carrying two rows ofelectrical connectors extending longitudinally thereof. With this formthe parts are often arranged with a view to ensuring that the electricalengagement can be effected only when the housings have firstly beencorrectly aligned and orientated with respect to one another. In oneknown arrangement two keyways of rectangular form are disposed in one ofthe housings at opposite ends of the rows of electrical connectors, anda pair of keys is disposed in the other housing to mate with respectiveones of the keyways, the keys being arranged to slide along theirrespective keyways when the two housings are urged together to establishthe electrical mating. The two keyways, and similarly the keys matingwith them, are provided with different cross-sectional dimensions fromone another, with a view to inhibiting mechanical engagement of thehousings unless they are correctly orientated with respect to oneanother. Such an arrangement is effective to prevent mating of allconnectors of one part with respective connectors of the other part,unless these housings are correctly aligned and orientated. However, ithas been found that such an arrangement is not completely foolproof inthat it is still possible in some states of incorrect alignment ororientation of the housings to obtain mating of some electricalconnectors of the two parts.

With a view to overcoming this disadvantage, it has further beenproposed to provide one of the housings additionally with a locating pinwhich is off-set with'respect to the center of that housing, and toprovide the other housing with a hole which is positioned to co-operatewith the locating pin only when the housings are correctly aligned andorientated. Such an arrangement has been found substantially to overcomethe aforementioned disadvantage but itself suffers from a number ofdisadvantages. One of these disadvantages is that the locating pin mustessentially extend beyond the ends of the electrical connectors carriedby its housing and is therefore liable to be snapped off if the twohousings are brought together in incorrect alignment or orientation. Afurther disadvantage is that the locating pin and its co-operating holereduce the space available for the electrical connectors on thehousings, and hence reduce the number of electrical connectors that maybe carried by the housings.

According to the present invention there is provided an electricalcoupling comprising two parts that are adapted to engage one another ina unique mechanical engagement before they can be finally urged togetherto establish the mating of electrical connectors of one of the partswith respective electrical connectors of the other part, wherein saidmechanical engagement includes essentially the insertion of a key of onepart into a mating keyway of the other part to slidefurther along thekeyway as the two parts are urged together in the establishment of themating of the connectors with one another, and wherein the key and thekeyway each have a transverse section that is in the form of a sawtoothwith unequal flanks such that establishment of the mating of theconnectors can be effected only following the said mechanical engagementof the two parts.

A two-part electrical coupling in accordance with the invention will nowbe described, by way of example, with reference to the accompanyingdrawings in which:

F IG. 1 is a sectional end view of the coupling which consists of a plugand socket;

FIG. 2 is an underneath plan view of the plug;

FIG. 3 is a side view of the plug;

FIG. 4 is a sectional plan view on the line AA of FIG. 3;

FIG. 5 is an underneath plan view of the socket;

FIG. 6 is a side view of the socket; and

FIG. 7 is a plan view of the socket.

Briefly, the plug and socket each include a molded housing of elongateform having apertures, for receiving electrical connectors, disposed intwo parallel rows extending longitudinally of the housings. At the endsof the rows of connectors the housings are provided with locatingsurfaces which are so shaped that the locating surfaces of the socketwill mate with the respective locating surfaces of the plug only whenthe housings are correctly aligned and orientated with respect to oneanother. The locating surfaces thus provide for a unique mechanicalengagement between the housings of the plug and socket and it isarranged that mating of the respective pairs of plug and socketconnectors can be effected only when the respective locating surfaceshave been mated together.

With reference to FIGS. 1 to 4, the plug includes a molded housing 1 ofplastic which is of elongate form and has two rows of holes extendinglongitudinally thereof. Each hole has inserted therein an electricalconnector 2 having pins 3 and 4 which project upwardly and downwardlyrespectively from the housing 1. The connectors 2 are inserted into theholes from the bottom of the housing 1, and have, intermediate the pins3 and 4, parts 5 of increased diameter which provide circumferentialshoulders that engage circumferential shoulders in the holes to limitthe extent of insertion of the connectors 2 into their holes. The lowerends of these holes are countersunk to assist insertion of theconnectors 2. The pins 3 have parts 6 of increased diameter, theconnectors 2 being retained in position by circlips 7 which surround thepins 3 between the parts 6 and the upper surface of the housing 1.

The housing 1 has on its upper surface a wall 3 which extendslongitudinally of the housing 1 between the two rows of pins 3, andwalls 9 which extend transversely of the housing 1 between each pair ofadjacent pins 3. The wall 8 and the parts of the walls 9 between the tworows of pins 3 have a height which is less than that of the other partsof the walls 9, to provide a longitudinal slot 10 (shown in FIG. 1)adapted to receive an edge of a printed circuit board 1 l.

The board 11 has a printed circuit on each side thereof, the conductorsof the printed circuits being connected by leads (not shown) toappropriate ones of the pins 3. These leads are conveniently wound roundthe respective pins 3 by a wiring tool. The board 11 is secured to lugs12 provided at the ends of the housing 1.

The housing 1 also includes two transverse walls 13 which are positionedat respective ends of the housing 1 and which project downwardly fromthe lower surface of the housing 1 beyond the ends of the pins 4. Thesides 14 of the walls 13 are shaped to form keyways (shown most clearlyin FIG. 2) which, as will be described hereinafter, mate with respectivekeys on the socket shown in FIGS. 1, 5, 6 and 7. More specifically, thekeyways are each bounded by a pair of convergent and conterminous flanksof unequal lengths that are joined at a point intermediate the width ofthe respective keyways so that the transverse sections of the keywaysare, as shown in FIG. 2, each in the form of a sawtooth and have a widthwhich is very nearly equal to the width of the housing 1. The lower endsof the sides 14 are chamfered to assist mechanical engagement of theplug and socket. Y

The lower face of the housing 1 is stepped at each side as shown inFIG. 1. Y

The socket is shown in FIGS. 1, S, 6 and 7, and comprises a mouldedhousing 16 of plasticshaving holes in which are inserted electricalconnectors 17 for engaging respective pins d of the electricalconnectors 2 carried by the plug. The electrical connectors 17 areinserted into the tops of the holes in the housing 16 and comprisesockets 18, for receiving the respective pins 4, housed within thehousing 16, and pins 19 which project downwardly from the underside ofthe housing 16. The connectors 17 have parts 20 (shown in FIG. 1) whichhave circumferential shoulders and engage circumferential shouldersprovided in the holes in the housing 16 to limit the extent of insertionof the connectors 17 into these holes. The tops of these holes arecountersunk to assist insertion of the connectors 17. The pins 19 haveparts 21 of increased diameter, the connectors 17 being retained inposition by circlips 22 which surround the pins 19 between the parts 21and the underside of the housing 16.

The housing 16 has a longitudinal wall 23 which extends between the tworows of pins 19 and has walls 24 which extend transversely of thehousing 16 between each pair of adjacent pins 19.

The upper face of the housing 16 is stepped so that this face has fullsurface abutment with the stepped lower face of the housing 1 when theplug and socket are fully engaged with one another, as shown in FIG. 1.

The housing 16 has transverse end-surfaces 25, shown most clearly inFIG. 7, that are shaped to form keys which mate with respective keywaysof the plug shown in FIGS. 1 to 4. The keys are each bounded by a pairof convergent and conterminous flanks of unequal lengths that are joinedat a point intermediate the width of the respective keys so that thetransverse sections of the keys are, as shown in FIG. 7, each in theform of a sawtooth and have a width which is very nearly equal to thewidth of the housing 16. The upper edges of the endsurfaces 25 arechamfered to assist mechanical engagement of the plug and socket.

When the plug is to be plugged into the socket to connect the electricalconnectors 2 electrically with their respective electrical connectors17, the electrical engagement is prevented until the end-surfaces 25 ofthe housing 16 have been mated with the walls 13 on the housing 1. Theshaping of the end-surfaces 25 and the walls 13 is such that they willmate only when the housings l and 17 are correctly aligned andorientated, thereby preventing incorrect electrical engagement betweenthe electrical connectors 2 and the electrical connectors 17.

The housing 16 has a mounting lug 26 at each end thereof.

When two-part electrical couplings are used in, for exam-.

ple, aircraft electrical equipment, moisture may enter the coupling andshort circuit adjacent pairs of the electrical connectors. In theelectrical coupling described, the likelihood of these short-circuitsoccurring is reduced by the walls 8 and 9, and the walls 23 and 24,which increase the moisture pathlengths between adjacent pairs of,respectively, the pins 3 and the pins 19 and thereby serve to improvethe climatic grading of the electrical coupling. The climatic grading ofthe electrical coupling is further improved by the steps in the abuttingfaces of the housings l and 16, which increase the moisture path-lengthsbetween the pins 4 and the sides of the housings l and 16.

Although in the embodiment described the electrical connectors 2 and 17are inserted into holes provided in the respective housings l and 16, itis visualized that the electrical connectors 2 and 17 may be molded asinserts in their respective housings l and 16.

We claim:

1. In an electrical two-part coupling of the kind in which the two partsof the coupling engage one another in mechanical engagement before theycan be finally urged together to establish the mating of a plurality ofparallel rows of electrical connectors of one of the parts withrespective electrical connectors of the other part, and each partcomprises a housing carrying the respective electrical connectors andincludes a plurality of locating surfaces extending transversely of therespective rows of electrical connectors, with the locating surfaces ofone housing engaging respective locating surfaces of the other housingto provide the said mechanical engagement, and the two locating surfacesof one of the mutually engaging pairs of surfaces defining respectivelya keyway and a key which is inserted in the keyway in said mechanicalengagement and which is slid further along the keyway as the two partsare urged together in the establishment of the mating of the electricalconnectors, the improvement that the key and keyway each have atransverse section that is m the form of a sawtooth having unequalflanks with the junction of the two flanks in said sawtooth spaced fromboth ends of the respective locating surface.

2. A coupling according to claim 1, wherein the said flanks of thesawtooth-section are conterminous.

3. A coupling according to claim 2, wherein the key and keyway arecompletely bounded by their respective pairs of flanks, and the junctionof each pair of flanks is intermediate the width of the respective keyor keyway.

4. A coupling according to claim 3, wherein each said housing includestwo parallel rows of electrical connectors, and the junction of the pairof flanks on that housing is located in alignment with one of theserows.

5. A coupling according to claim 1, wherein each housing is of elongateform and includes two said locating surfaces ex tending transversely ofthe housing at the two ends respectively of the rows of connectors.

6. A coupling according to claim 5, wherein the locating surfaces extendacross the whole widths of their respective housings, and the width ofthe keyway is very nearly equal to the width of its respective housing.

7. A coupling according to claim 1 1, wherein the two locating surfacesof each mutually-engaging pair of surfaces define respectively a key andkeyway that each have a transverse section in the form of a sawtoothwith unequal flanks with the junction of the two flanks of the sawtoothspaced from both ends of the respective locating surface.

8. A coupling according to claim 7, wherein one housing includes all ofthe keys and the other housing includes all of the cooperating keyways.

9. A coupling according to claim 1, wherein the said housing haverespective co-operating faces for abutting one another when the twoparts are fully mated, the said cooperating faces having co-operatingsteps for increasing the moisture path-lengths from the exterior of thecoupling to the electrical connectors when the said parts are fullymated.

10. A coupling according to claim 1, wherein the electrical connectorsare removably-mounted in the said housing.

$223330 v v UNL'ULU DJJLLLD Inn 1 VLHWU C TE OF GORRECTIQN Patent NO-Dated April ll,

Inventor) Thom as Victor MCDONALD and KENNETH MCDONALD STOCKLEY It isvcertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Foreign Application Priority Date II'IOII QI'Q. Signed and sealed this22nd day of August 1972 (SEAL) Attest:

ROBERT'GO'ITSCHALK Commis sionert of Patem ED ARD M,FLETGHER,JR.Attesting Officer

1. In an electrical two-part coupling of the kind in which the two partsof the coupling engage one another in mechanical engagement before theycan be finally urged together to establish the mating of a plurality ofparallel rows of electrical connectors of one of the parts withrespective electrical connectors of the other part, and each partcomprises a housing carrying the respective electrical connectors andincludes a plurality of locating surfaces extending transversely of therespective rows of electrical connectors, with the locating surfaces ofone housing engaging respective locating surfaces of the other housingto provide the said mechanical engagement, and the two locating surfacesof one of the mutually engaging pairs of surfaces defining respectivelya keyway and a key which is inserted in the keyway in said mechanicalengagement and which is slid further along the keyway as the two partsare urged together in the establishment of the mating of the electricalconnectors, the improvement that the key and keyway each have atransverse section that is in the form of a sawtooth having unequalflanks with the junction of the two flanks in said sawtooth spaced fromboth ends of the respective locating surface.
 2. A coupling according toclaim 1, wherein the said flanks of the sawtooth-section areconterminous.
 3. A coupling according to claim 2, wherein the key andkeyway are completely bounded by their respective pairs of flanks, andthe junction of each pair of flanks is intermediate the width of therespective key or keyway.
 4. A coupling according to claim 3, whereineach said housing includes two parallel rows of electrical connectors,and the junction of the pair of flanks on that housing is located inalignment with one of these rows.
 5. A coupling according to claim 1,wherein each housing is of elongate form and includes two said locatingsurfaces extending transversely of the housing at the two endsrespectively of the rows of connectors.
 6. A coupling according to claim5, wherein the locating surfaces extend across the whole widths of theirrespective housings, and the width of the keyway is very nearly equal tothe width of its respective housing.
 7. A coupling according to claim11, wherein the two locating surfaces of each mutually-engaging pair ofsurfaces define respectively a key and keyway that each have atransverse section in the form of a sawtooth with unequal flanks withthe junction of the two flanks of the sawtooth spaced from both ends ofthe respective locating surface.
 8. A coupling according to claim 7,wherein one housing includes all of the keys and the other housingincludes all of the cooperating keyways.
 9. A coupling according toclaim 1, wherein the said housing have respective co-operating faces forabutting one another when the two parts are fully mated, the saidco-opeRating faces having co-operating steps for increasing the moisturepath-lengths from the exterior of the coupling to the electricalconnectors when the said parts are fully mated.
 10. A coupling accordingto claim 1, wherein the electrical connectors are removably-mounted inthe said housing.